Field of the Invention
The present invention relates to an imaging lens, and more particularly to an optical telephoto imaging lens.
Related Prior Art
In recent years, with the popularity of the mobile phone cameras, the optical lens system has become smaller in size, and the electronic sensor of a general digital camera is typically a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor. Due to advances in semiconductor manufacturing, the pixel size of sensor has been reduced continuously, and miniaturized optical lens systems have increasingly higher resolution. Therefore, there are increasing demands for an imaging lens system with better image quality, and for a telephoto imaging lens.
Conventional miniaturized lens systems used in portable electronic products mostly consist of four lens elements, however, since the high profile mobile devices, such as smart phone, wearable device, tablet personal computer, and infrared imaging lens, are becoming prevalent, the demand for resolution and imaging quality of the miniaturized lens system also increases. The conventional four-piece lens system cannot satisfy higher demand, and is unsuitable for telephoto imaging.
The conventional miniaturized imaging lens used in mobile devices, such as, mobile phone, tablet computer and other wearable electronic devices, such as the imaging lenses described in U.S. Pat. No. 7,436,600, 2013/0021677 and 2015/0131162, maybe suitable for telephoto imaging, however, the configuration is too complicated and large to be installed in a mobile device.
The imaging lenses consisting of five lens elements disclosed in U.S. Pat. Nos. 8,000,031, 8,508,860, and 8,395,851 have a simplified structure and are also small enough to be installed in the mobile device, but are still incapable of long distance imaging.
The present invention has been made in order to solve the above-mentioned problems.